Pipette



March 13, 1956 p. 0. K. HAAK PIPETTE Filed June 23, 1952 U M w MK m a wL A u a w alth United States Patent 'ce PIPETTE Paul 0. K..Haak, SanFrancisco, Calif.

Application June 23, 1952, Serial No. 294,980

' Claims. c1. 73-4254 Another object of the invention is to provide apipette wherein an exact amount of blood is drawn by capillaryattraction, and wherein an exact amount of diluting fiuid is also drawnand measured by capillary attraction so as to be evenly mixed with theblood and from which the diluted blood can be safely and easily appliedupon the usual slide or counting chamber.

I am aware that some changes may be made in the general arrangements andcombinations of the several devices and parts, as well as in the detailsof the construction thereof without departing from the scope of thepresent invention as set forth in the following specification, and asdefined in the following claims; hence I do not limit my invention tothe exact arrangements and combinations of the said device and parts asdescribed in the said specification, nor do,I confine myself to theexact details of the construction of the said parts as illustrated inthe accompanying drawings.

With the foregoing and other objects in view, which will be mademanifest in the following detailed description, reference is had to theaccompanying drawings for the illustrative embodiment of the invention,wherein:

Fig. l is a side viewof my pipette, and,

Fig. 2 is a sectional view of my pipette on an enlarged scale.

In carrying out my invention I form a measuring or induction tube 1 withan outer bent tip 2 projecting to one side of the tube for facilitatingthe intake of blood and the discharge of diluted blood.

At the other end or top of the induction tube 1 is a bulb or mixingchamber 3. The upper or inner end of the tube 1 has thereon a bentprojecting tube 4 which projects generally centrally into the mixingchamber 3 and is bent to one side generally oppositely to the directionin which the intake tip 2 is bent.

A capillary passage 5 extends through the tube 1 from the tip 2 to theend of the projecting tube 4 and ends abruptly at the inner end of theprojecting tube 4 without any material change in its cross sectionalarea which is substantially uniform.

From the top of the mixing chamber 3 extends a drawing tube 6 axiallyaligned with the induction tube 1. 'In this drawing tube 6 is a drawingchamber 7. A wall 8 on the top of the mixing chamber 3 separates it fromthe drawing chamber 7. An inner measuring tube 9 projects from this wall8 into the drawing chamber 7 and is surrounded by the latter. An uppercapillary passage 11 2,737,812 Patented Mar. 13, 1956 extends throughthe separating wall 8 and said projecting tube 9 and ends abruptly atthe top of the projecting tube 9 so as to determine the exact amount ofdiluting fluid drawn into the pipette. A drawing passage 12v extendsfrom the top of the drawing chamber 7 to the upper end of the drawingtube 6. All the passages 5, 11 and 12 are in alignment.

A pair of cars 13 extend outwardly from opposite sides of the inductiontube 1 and are bent upwardly at their tips so as to accommodate holes 14in a flexible closure strap 16 which latter is plastic so as to betightly held over the end of the outer tip 2 of the induction tube l'forsealing the fluid in the pipette.

A mixing bead 17 in the mixing chamber 3 is loose but it cannot blockthe induction capillary passage 5 because the bent inner tip 4 extendswell into the mixing chamber 3 and is bent laterally. Thus the bead 17can never come to rest against the inner end of the capillary passage 5.In operation the tip 2 of the induction tube 1 is touched against orimmersed into the emerging drop of blood from finger or ear, and theblood will rise in the capillary passage 5 until it reaches the upperend of the passage 5 at the tip of the inner bent end 4 where it stopsbecause the capillarity stops at the tip of said end 4. This holds anaccurately measured quantity of blood. Then the tip 2of'the tube 1 isimmersed in a suitable diluting fluid and suction is applied through thedrawing tube 12 to draw the diluting fluid through the lower capillarytube 5 into the mixing chamber 3 and begin the drawing of the mixtureinto the upper capillary passage 9. The mixture will then rise to thetop of the upper capillary passage 9 and will stop there because thesecond passage 9 stops abruptly inside the drawing chamber 7. Thus theamount of diluting fluid is also measured accurately and automaticallywithout the need of visual observation, and a precisely accuratedilution and mixture is accomplished. By stretching the elastic closurestrip 16 over the tip 2 and hooking it on the ears 13 the pipette issealed for transportation for testing the blood. After uncovering thetip again and by touching it upon a slide or counting chamber a suitabledrop of the diluted blood can be discharged for testing.

As the blood and diluting fluid are drawn from the lower capillarychamber 5 into the mixing chamber 3 it is prevented from rushingupwardly into the upper passages because the inner bent tip 4 of theinduction passage forms a trap in mixing chamber 3 and directs the flowof the solution against the opposite side wall of the mixing chamber 3,and allows the solution to fall downward and rise gradually as it fillssaid mixing chamber 3. Thus the mixing chamber 3 is filled evenly andfree of air bubbles and affords accurate measurement of the solution.The pipette may be shaken at suitable times to cause the bead therein tomix the contents of the mixing chamber 3.

The device is simple, efiicient and accomplishes uniformly accurateresults, reducing human errors to a minimum. The forming of air bubblesand pockets is efiectively prevented by the combination of chambers andcapillary passages, and are further minimized by the gradual curving orflaring of the chambers toward their top or outlet passages, as shown atthe top of the mixing chamber 3 in Fig. 2.

I claim:

1. A pipette comprising a tube, a mixing chamber formed in said tube,said tube containing a capillary intake passage leading into said mixingchamber, a second chamber formed in said tube spaced from the top of themix ing chamber, a dilution measuring capillary passage between saidmixing chamber and said second chamber, and

a projection extended into said second chamber containing a continuationof said dilution measuring passage.

2. A pipette comprising a tube, a mixing chamber formed in said tube,said tube containing a capillary intake passage leading into said mixingchamber, and a capillary dilution measuring passage extending from thetop of said mixing chamber, a loose mixing bead in said mixing chamber,and a projection with a laterally bent end extending in continuation ofsaid capillary intake passage and projecting into and being surroundedby said mixing chamber and pointing toward a side of said mixing chamberso as to prevent said mixing bead from stopping said capillary intakepassage.

3. A pipette comprising a tube, a mixing chamber formed in said tube,said tube containing a capillary intake passage leading into said mixingchamber, a second chamber formed in said tube spaced from the top of themixing chamber, and a projection having a dilution measuring capillarypassage projecting into and being surrounded by said second chamber.

4. A pipette comprising a tube, a mixing chamber formed in said tube,said tube containing a capillary intake passage leading into said mixingchamber, a second chamber in said tube spaced above from the top of saidmixing chamber, and said tube containing a capillary dilution measuringpassage extending from the top of said mixing chamber to said secondchamber, a laterally bent tubular projection surrounding the end of saidcapillary intake passage and projecting into and being surrounded bysaid mixing chamber and pointing toward a side of said mixing chamber,and a tubular projection around the end of said dilution measuringcapillary passage projecting into and being surrounded by said secondchamber.

5. In a pipette, an intake tube having capillary passage therethrough, amixing chamber at the end of the intake tube, a mixing bead looselypositioned in said mixing chamber, a projection extended from the bottomof the mixing chamber inwardly of the chamber and bent at an angle tothe axis of said tube pointing toward a side of said mixing chamber andhaving a capillary passage therethrough in continuation of said passagein the tube to conduct liquid into the mixing chamber laterally and toprevent obstruction of flow by said mixing bead, and an intake end onsaid tube being bent generally oppositely to the direction of thedischarge from said projection.

References Cited in the file of this patent UNITED STATES PATENTS553,044 Sharples Jan. 14, 1896 694,530 Comer Mar. 4, 1902 1,433,075Gottlieb Oct. 24, 1922 1,594,370 Kubota Aug. 3, 1926 1,678,540 TrennerJuly 24, 1928 1,791,829 McCrackan Feb. 10, 1931 2,104,325 Juifa Jan. 4,1938 2,158,102 Betzold et al May 16, 1939 2,638,787 Flaig et al May 19,1953 OTHER REFERENCES Fisher Catalog 90 Modern Lab. Appliances, FisherScientific Co. N. Y. (1942 catalog.)

1. A PIPETTE COMPRISING A TUBE, A MIXING CHAMBER FORMED IN SAID TUBE,SAID TUBE CONTAINING A CAPILLARY INTAKE